Strong electronic correlations and magnetism in systems containing transition metals and lanthanides
Title: Strong electronic correlations and magnetism in systems containing transition metals and lanthanides
SNIC Project: SNIC 2020/5-592
Project Type: SNIC Medium Compute
Principal Investigator: Igor Dimarco <igor.dimarco@physics.uu.se>
Affiliation: Uppsala universitet
Duration: 2020-12-01 – 2021-12-01
Classification: 10304 10407
Homepage: http://fplmto-rspt.org/
Keywords:

Abstract

In this project, we plan to use density functional theory (DFT) and its combination with dynamical mean field theory (DMFT) to investigate various problems, grouped in three major lines of research. Our first line of research is focused on understanding the competition between charge density waves and magnetism in transition metal dichalcogenides, namely VS2, VSe2, NbS2 and NbSe2. The possibility to synthesize these materials in thin films or even single layers, opens doors to exciting behaviors and functionalities to be used in future nano-electronic devices. We are particularly interested in controlling the magnetic properties at the microscopic level via strain, which can be achieved by means of different substrates. Electronic structure calculations will be performed to understand how a variety of magnetic phases can be stabilized via anisotropic strain. The resulting magnetic phases will be then investigated via atomistic spin dynamics to understand their stability with respect to thermal fluctuations. Modeling of scanning tunneling microscopy experiments will be also performed, to ensure a more direct comparison with past and future experimental data. Our second line of research is focused on Lanthanide adatoms deposited on graphene. In our recent work [PRX 10, 031054 (2020)], we calculated accurate intra-atomic exchange energies in DFT via our in-house code RSPt. We now intend to extend this analysis to include a more accurate description of the strong electronic correlations via DFT+DMFT, which may affect the bonding distances as well as the magnetism itself. The competition of crystal field-effects and magnetism is particularly interesting from a methodological point of view, and can be analyzed at different levels of accuracy. We also plan to extend our methodology to include anisotropic contributions to the intra-atomic exchange, which are traditionally neglected. The formalism and the developed code are going to be important to provide a robust connection between electronic structure theory and the sd exchange model of magnetism, which can also be applied for future data mining projects. Finally, our third line of research is focused on Bi thin films. Bi is characterized by a strong spin-orbit coupling, which can induce a Rashba-type spin splitting of its surface states, as well as modify the conducting properties. Thin films may be grown on different substrates, altering their crystal structure, as e.g. via buckling, and hence their electronic properties. Bi grown on InAs is particularly interesting as a pathway to engineer low-dimensional nano-structures via self assembly. Experimental characterization is however difficult and needs to be accompanied by an extensive theoretical support. We intend to perform a comprehensive ab-inito study of Bi nanolines on Bi/InAs(100), currently missing in literarure. Our main aim is to verify the origin of the flat bands close to the Fermi energy that are visible in the experimental data obtained via angle-resolved photoemission spectroscopy (ARPES) by our collaborators at Cergy-Pontoise University, France. These features are a unique way to discriminate among different accessible configurations and can deliver important information on this system.